The present invention relates to a gas barrier laminate using a biaxially-oriented polypropylene film (hereinafter referred to as an OPP film) base, and a method for producing the gas barrier laminate.
Packaging materials used for packaging food products, non-food products, or pharmaceutical products are required to prevent degradation of the products and retain the functions and nature of the products. To this end, the packaging materials are required to have impermeability to oxygen, moisture, and other gases that degrade the products. As such packaging materials, gas barrier laminates are well known.
Such gas barrier laminates generally use metal foils such as of aluminum as gas barrier layers. Gas barrier layers such as of aluminum foils are unlikely to be influenced by temperature/humidity changes or the like. It is true that the packaging materials using metal foils such as of aluminum are unlikely to be influenced by temperature/humidity changes and thus have good gas barrier properties. However, such packaging materials have problems, for example, that the products cannot be seen and recognized through the packaging materials, or the packaging materials have to be treated as incombustible materials when discarded after use, or metal detectors cannot be used for searching the packaging materials.
Packaging materials for overcoming these problems are under development. For example, using a forming method, such as vacuum deposition or sputtering, a vapor-deposited film of an inorganic oxide, such as silicon oxide or aluminum oxide, is formed on a polymer film, for use as a packaging material (e.g., see PTLs 1 and 2). Such vapor-deposited films are known as having transparency and properties for blocking gases, such as moisture. Further, the vapor-deposited films have an effect of improving adhesiveness relative to a laminated film and thus are favorable as packaging materials having transparency and gas barrier properties which cannot be achieved by metal foils, or the like.